Smelting of ferrc-alloys in blast furnaces



Patented ,lan,a l

l l93d it. 11 it W. DAVIS, (fill? MILFORD, DELA'WARE, ALfiSJIGl'NQJRI 'Jltl) SMdUlEL til. ALLEN, TRUSTEE Etta thawing.

This invention relates to the smelting of ferro-alloys in the blast furnace, and its nature, objects and advantages will be clear from the following a in the present smelting of ferro-alloys in the blast furnace the procedure is as follows:

The ore, flux and coke are charged into the top of the furnace. As this material travels downward it is subjected to the action of a in stream of hot reducing gas which heats the entire burden, calcines thelimestone, and reduces the iron oxide present. For example, let us consider the case of ferro-manganese, which will be characteristic of all ferro-alloy it smelting In this case the manganese oxide is heated by the hot ascending gas as the ore travels down the furnace, but no appreciable chemical reduction of the manganese oxide is accomplished. Vfhen the material reaches to the smelting zbne, the slag is formed and the manganese oxide is reduced in the presence of solid carbon and with high temperature heat.

An increase in the high temperature heat available ever present ractice by the use of mi oxygen enriched b ast will increase the action of the smelting zone. However, very little oxygen may be added before trouble would be experienced due to a deficiency of heat in the shaft, because of the consequent a relative reductionin volume of the ascending products of combustion which do the heating. The shaft section, however, conducts a stream of gas very high in G0, with high potential heat value. lit is proposed, therefore, that 35 oxygen be admitted to the shaft at points above the mantle to edect a combustion of this gas, the heat generated supplying the shaft deficiency which would otherwise-occur,

if this were practiced with. coke present in the burden, the oxygen admitted in the shaft as well as the U9 formed would attach the coke converting a portion of it to CU and decreasing the amount of coke which would pass to the smelting zone. it is therefore proposed in this process to introduce the major ortion or all of the fuel at the tuyere level. lhis fuel may be admitted as a powder or as a liquid.

Briefly then the process consists of blowing the furnace with an oxygen enriched blast,

application filed lune ll, that,

admitting fuel at the tuyere zone, and by using additional oxygen admitted tothe shaft to convert the potential heat in the top gas and transmit it as sensible heat to the bur- 'llhe enrichment of the blast cuts down the relative proportion of nitrogen in the blast and, therefore, the relative volume of gases leaving the smelting zone is less. Stated in another way, the volume of gases leaving the zone per unit of fuel is less. This concentrates the heat in the smelting zone in great degree, because there is relatively less heat carried 0d by the gases leaving the zone, Hence, smelting is expedited, which results in a more rapid movement of the descending burden with more material fed in less time. The deficiency in heat in the shaft is made up as above pointed out. Stated in another way, there is not only an increase in tonnage but also greater e'lhciency.

, Furthermore, the exit temperature of the top gases is lowered and values heretofore carried out as vapor, are condensed and thus recovered.

in addition, the process increases the rate of smeltin without increasing blast pressure beyond allowable limits, this being a consequent of the utilization of a supporter of combustion which will remove carbon at a faster rate than usual, without relatively increasing the volume of gases leaving the smelting zone.

The process is applicable to other ferro alloys than the ones mentioned, and the term oxygen is employed in a broad sense.

The oxygen or oxygenated air may be added to the usual blast or a gas richer in oxygen than air, produced b any suitable means,'may be employed in en stitution for the usual blast. as

By my invention it is also possible to dispense with heating the blast and the stoves employed for this purpose.

I claim:

l, lin the reduction of ferro-alloys in the blast furnace, the increase of high tempera ture heat above the critical temperature by the addition of a supporter of combustion to the blast reducing the relative volume of gases leaving the smelting zone, in admitting fuel in 10o tit) lid

lit

lid

the region of the tuyres and in introducing into the shaft a supporter of combustion.

2. In the reduction of ferro-alloys in the blast furnace, the process which consists in blowin with an oxygen enriched blast, in admitting a supporter of combustion to the shaft for the utilization of the potential heat in the shaft by the conversion of CO into CO and in introducing fuel in the region of the tuyres.

In testimony whereof, I have hereunto si ed m name.

gn y FRANK W. DAVIS. 

